1. Field of the Invention
The present invention relates to relay units and more specifically to relay units for optical devices for use in television cameras, video cameras, television lens, video lens, or the like, which perform automatic focal point detection focus control (hereafter referred to as “AF control”).
2. Description of the Related Art
In recent years, automatic focal point detection control (AF) control has become indispensable to picture-taking devices such as consumer-grade video cameras or the like. The AF control method extracts and evaluates signals corresponding to the sharpness of the subject from picture signals before automatic focal point detection is performed.
An example of operations of such an AF control system is described with reference to FIG. 6. In FIG. 6, reference numeral 600 denotes a camera with a non-detachable lens unit, 102 denotes evaluation value generating means for extracting a sharpness evaluation value from the picture signals output from later-described process means 202, and 103 denotes AF driving control means for generating motor control signals such that the sharpness evaluation value generated by the evaluation value generating means 102 is maximized. Reference numeral 105 denotes a motor operated under the control of the AF driving control means 103, and 106 denotes a focus lens which is driven along the optical axis by the motor 105. Reference numeral 201 denotes a CCD, 202 denotes process means for converting the output signals of the CCD into a picture format such as NTSC signals or the like, and 203 denotes recording/reproducing means for recording the picture signals, which are the output of the process means 202, on a recording medium, and reproducing the pictures recorded therein.
In the above-described configuration, the optical flux which has passed through the focus lens 106 is imaged on the imaging face of the CCD 201 for photoelectric conversion by the CCD. A held sample is then input to the process means 202, where input signals are converted into a picture format such as NTSC signals or the like, and output to the evaluation value generating means 102 and the recording/reproducing means 203. The evaluation value generating means 102 generates sharpness evaluation values for the picture signals output to the evaluation value generating means 102, the sharpness evaluation values relating to the frequency component of the picture being obtained by filter processing or the like and generated in increments of vertical synchronization cycles of the picture signals, and output to the AF driving control means 103. At the AF driving control means 103, motor control signals are generated which move the focus lens 106 to a position wherein the sharpness evaluation value is maximum, sequentially comparing the sharpness evaluation value in increments of vertical synchronization cycles while driving the motor 105, so that the focus lens 106 is moved to the focal point. The recording/reproducing means 203 records the output of the process means 202 in the recording medium, and also reproduce the pictures recorded therein.
An example of such AF driving will be described. The movement direction of the focus lens 106 is determined by moving the focus lens 106 by a small amount. That is, the focal point may either be at the far side of the near side of the current position of the focus lens 106 or the near side of the focus lens. By slightly moving the focus lens 106, and considering the change in the sharpness evaluation value, such movement direction is determined. Subsequently, the focus lens 106 is moved at a specific speed in order to detect the peak value of the sharpness evaluation value, following the results of determining the direction for driving. This is referred to as “hill-climbing determination”. After exceeding the peak value, the direction of moving the focus lens 106 is reversed, and the focus lens 106 is guided in increments of minute amounts of movement so that the sharpness evaluation value is maximized. This is referred to as “peak determination”. Following the peak determination, the sharpness evaluation value is read and compared with the value immediately following the peak determination, and the value has changed, the AF operations are reactivated.
The video AF actions of a camera system having such an exchangeable lens configuration is described in detail in Japanese Unexamined Patent Application Publication No. 9-065184.
Also, “remote systems” are known for monitoring and/or taking pictures of ceremonies or other solemn services or gatherings, etc., by using television cameras, video cameras, television lenses, video lenses, and so forth. Such remote systems are not equipped with AF control, and thus require an operator to operate switches and dials to perform functions such as zooming, iris control, focus, and so forth.
A remote system uses a 12-pin electric interface between the remote control unit and the camera. The electric interface has pins assigned to zoom, iris, and focus command signals, control mode signals (switching between speed control and position control), electric power source, ground, and so forth. In may such remote systems, all 12 pins are in use, i.e., there are no more pins available.
An example of operations of this remote system is described with reference to FIG. 7. The components in FIG. 7 denoted by the reference numerals 105, 106, 201, 202, and 203, in FIG. 6, have already been described above, and accordingly description thereof will be omitted here.
In FIG. 7, reference numeral 100 denotes an exchangeable lens unit, 200 denotes a camera unit, and 400 denotes a remote control unit for supplying to the lens unit 100: command signals for controlling an unshown zoom lens unit, iris unit, and focus lens 106; and switching signals for switching between either speed control or positional control to control the unshown zoom lens unit, iris unit, and focus lens 106. Reference numeral 500 denotes a remote control cable connecting the lens unit 100 and the remote control unit 400.
In the lens unit 100, reference numeral 107 denotes a remote control input terminal for inputting to the lens unit 100 the command signals and switching signals from the remote control unit 400, 109 denotes MF driving control means for generating motor control signals for driving a motor 105 from manual focus command signals (hereafter referred to as “MF command signals”) input from the remote control unit 400, and 211 denotes S/P (Speed/Positional) switching signal determining means for outputting S/P switching command signals to the MF driving control means to control the focus lens 106 with either speed control or positional control, based on S/P switching signals output from S/P switching signal input means 402.
In the remote control unit 400, reference numeral 401 denotes MF command signal generating means comprising switches and dials and the like for generating MF command signals, 402 denotes S/P switching signal input means to switch between control of the focus lens 106 with either speed control or positional control, and 403 denotes a remote control output terminal for outputting the MF command signals and S/P switching signals from the remote control unit 400 to the lens unit 100.
In the above-described configuration, operating the MF command signal generating means 401 causes MF command signals proportionate to the operations thereof to be output, and input to the MF driving control means 109 via the remote control input terminal 107. Also, S/P switching signals for switching between speed or positional control of focus lens 106 are output at the S/P switching signal input means 702, and input to the S/P switching signal determining means 211 via the remote control output terminal 403, the remote control cable 500, and the remote control input terminal 107. At the S/P switching signal determining means 211, determination is made regarding whether to control the focus lens 106 with speed control or with positional control, and the determination results are output to the MF driving control means 109 as S/P switching command signals. At the MF driving control means 109, in the event that the S/P switching command signals are for controlling the focus lens 106 with speed control, the MF command signals are handled as speed control commands signals, motor control signals are generated for driving the motor 105 at a speed commanded by the MF command signals, and the motor 105 is driven so as to move the focus lens 106. On the other hand, in the event that the S/P switching command signals are for controlling the focus lens 106 with positional control, the MF command signals are handled as positional control commands signals, motor control signals are generated for driving the motor 105 to the position commanded by the MF command signals, and the motor 105 is driven so as to move the focus lens 106.
However, with the above-described conventional example, in the event that the remote system has AF control, simply replacing the lens unit 100 with a lens unit capable of handling AF control does not provide the remote control unit 400 (which also enables remote operations of the lens unit 100) with switching means to determine whether the focus lens 106 is to be driven by AF control or MF control.
Also, with the remote system, there are no pins available in the electric interface between the remote control unit 400 and the lens unit 100, so pins cannot be assigned to switching signals to drive the focus lens 106 either by AF control or by MF control from the remote control unit 400.